Production of lubricating oils



Patented July 10, 1951 W V v 2,560,479

PRODUCTION OF LUBRICATING OILS George Riethcf, Pittsburgh, Charles W. Montgomery, Oakmont, and George P. Brown, Jr., Pittsburgh, Pa assignors to Gulf Research & Development Company, Pittsburgh, Pa., a corporation of Pennsylvania N Drawing. Application February 3, 1949, Serial No. 74,464-

7 Claims; (01. 196-40) The present invention is directed to a process for the production of lubricating oils. More particularly, it is directed to the preparation of lubricating oils and petroleum sulfonates using solvent extracts of distillate lubricating oil stocks.

' In accordance with the present invention, we have discovered that excellent yields of lubricating oils which are of particular value when blended with other lubricating oils can be obtained from solvent extracts of distillate lubricating oil stocks, while simultaneously obtaining oils suitable as fuel oils and cracking stocks, and also producing good quality petroleum sulfonates, by treating the extracts as described below.

The solvent extracts employed in the process of the invention are the extracts obtained by solvent extracting a distillate of a lubricating oil stock with solvents such as furfural, nitrobenzene, phenol, sulfur dioxide, dichloro-diethyl ether, and mixtures of propane and cresylic acid by'conventional methods designed to produce a good grade rafiinate oil. These methods, espe cially when using as the solvent furfural, phenol or nitrobenzene, usually result in .the production of solvent extracts containing a substantial amount, at least 15 per cent by weight of. the extract and frequently of the order of 30 to 50 per centor more, of hydrocarbons boiling Within the range of 300 to 400 C. at mm. mercury absolute pressure. The amount of hydrocarbons boiling within this range appearing in the solvent extract is dependent upon a number of well-understood factors, principal ones being the nature of the solvent, the amount of the solvent used, the nature of the stock, and the method of contacting. The solvent extracts with which this invention is primarily concerned are those which contain at least per cent and preferably at least 30 per cent, by weight of the extract, of hydrocarbons boiling within the range mentioned above. While the process is operative for the treatment of solvent extracts containing a lesser amount of hydrocarbons boiling within this range, its use is not attractive because of economic considerations.

We have found that although the lubricating oils prepared from these extracts by the process of the invention have relatively low viscosity indices, by combining such an oil with a major proportion of a lubricating oil having an S. A. E. number of at least 40 and preferably having a viscosity index within the range of about 40 to '60 viscosity index units higher than the viscosity index 'of the recovered oil; the resulting blended oil has a viscosity index at least of the order of weight of the solvent extract. The distillate fraction (or fractions, if more than one is collected) is then treated by a procedure compris-I ing sulfonating the fraction under mild condi-' tions, which results in the production of a mix ture containing an unreacted oil and sulfonic acids substantially free of contaminating sludge; i. e., materials which are insoluble in aqueous alkali solutions. By settling the mixture, separating the oil layer and the acid layer, neutralizing the sulfonic acids in the acid layer, and removing oil-soluble sulfonic acids from the oil layer, a valuable lubricating oil of good blending characteristics and good grade sulfonates are obtained. The residual oil remaining after the distillation of the extract is a useful fuel oil stock and if any distillate fractions are obtained other than the fraction or fractions subjected to the sulfonation, they may be used as light fuel oils or as charge to a cracking process.

In a preferred embodiment of the invention, a furfural extract of a lubricating oil distillate prepared so as to contain 30 to 40 per cent by weight of the extract of hydrocarbons boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure, and preferably after removal of the bulk of the furfural, is fractionally distilled and the fraction of the ex tract boiling within the range of about 300 to 400 C. at 10 mm. mercury absolute pressure is collected. This fraction is excellently suited for use as a lubricating oil blending component after additional treatmentas described immediately below. In this distillation one or more additional fractions may be obtained. The residue from this distillation is a heavy oil suitable for use as a residualfuel oil and the other distillate fractions are suitable for use as fuels or cracking stocks. The 300 to 400 C. fraction is additionallytreated by contacting it. with sulfuric acid containing 90 to 100 per cent H2804 and preferably under mild conditions of temperature, time, and amount of acid employed. The products resulting from this treatment are a lubricating oil fraction amounting to about to percent by weight of the distillate fraction which was sulfonated and having excellent blending qualities with high viscosity lubricating oils in that the blended oils have good viscosity-temperature characteristics; and sulfonic acids which upon neutralization form petroleum sulfonates which are substantially free of contaminating sludge and which can be used directly without additional purification. Also, valuable sulfonates are recovered from the oil layer formed in the sulfonation.

The process, therefore, not only is productive of excellent yields of oils which have excellent qualities for blending with other lubricating oils, but also of useful distillate and residuum fractions as well as substantially pure petroleum sulfonates adapted for immediate use; for example, for use as detergents. The original lubricating oil stock is thereby efliciently converted into useful products without wastage of hydrocarbon materials or sulfonic acids, and the problems caused by the formation of sludge are substantially eliminated.

v In practicing the invention in accordance with a preferred specific embodiment, the distillate lubricating oil stock is prepared by distilling the crude charge oil at temperatures below 760 F. under a vacuum of about 28 inches of mercury, in order to minimize (i. e. to avoid completely or substantially completely) cracking and the production of sludge-forming materials. During the course of the distillation about 2 to pounds of steam per barrel of charge oil are injected into the still to speed up the distillation process and help to avoid cracking. Distillates produced in this manner are substantially free of olefinie and asphaltic materials, as indicated by their light color and by low bromine numbers, which are in the neighborhood of about 2.

The lubricating oil distillate stock boiling beobtained may be finished by clay treatment and is then ready for use or for blending with other oils. The extract, which under these conditions will contain of the order of 30 to 50 per cent by weight of hydrocarbons boiling within the range of about 300 to 400 C. at 10 mm. mercury absolute pressure, is subjected to fractional distillation and a fraction boiling within the above range is collected.

The sulfonation of this fraction is accomplished under mild conditions and preferably with sulfuric acid of about 93 to 98 per cent concentration, and at substantially atmospheric temperatures. An amount of acid ranging from about 30 to about 50 per cent by weight of the oil is added to the oil at atmospheric temperature in one or more dumps, while vigorously agitating the mixture to insure intimate contact of the oil and acid. If more than one dump is used, the acid layer is separated after each dump. The time of contacting is preferably less than about 5 hours to avoid overtreatment, which in extreme cases may result in the formation of sludge.

After the sulfonation is completed, the acid oil layer is settled out and separated from the spent acid layer by decantation, centrifuging or other suitable method. The acid oil is preferably neutralized with ethanolamine, using a sufiicient excess to dissolve the amine sulfonates and form a liquid layer, as disclosed in our application Serial No. 48,326, filed September 8, 1948, now

I]. S. Patent No. 2,519,930. This layer is separated from the oil layer and the desired sulfonates are recovered by the addition of caustic soda and evaporating the amine. The oil layer is freed of dissolved amine, and the recovered oil may be finished by clay percolation to form a finished lubricating oil blending stock. The spent acid layer is diluted with water and neutralized with a basic material such as caustic soda. The sulfonates are then recovered by conventional methods to produce valuable sulfonates substantially free of resins and sludge.

Other distillate fractions may be obtained in the distillation of the extract. Such fraction are of value as cracking stock or fuel oil. The residuum from this distillation is a good quality residual fuel oil.

As previously indicated, the unreacted oil recovered after the sulfonation treatment, while having a relatively low viscosity index, is a useful lubricating oil. We have found that it is particularly valuable for blending with other lubricating oils; for example, by blending the oil in a minor proportion with a lubricating oil having an S. A. E. number of at least 40 an preferably having a viscosity index about 40 to 60 index units above the viscosity index of the unreacted oil, the resulting blended oil has a viscosity index at least of the order of that of the lubricating oil. The unreacted oil and the lubricating oil are preferably combined in such proportions that 100 parts by volume of the blended oil contains about 10 to 40 parts of the unreacted oil and about to 60 parts of the lubricating oil.

The following specific examples are given for the purpose of more clearly illustrating various embodiments of the invention.

Example I A furfural extract of a lubricating oil distillate of a coastal crude oil having, after the removal of substantially all of the furfural, the following properties:

Gravity, degrees A. P. I 14.2 Viscosity at F., centistokes 243.1 Viscosity at 210 F., centistokes 10.34 Viscosity index 90 was fractionally distilled under reduced pressure. A fraction boiling between 307 and 400 C. at 10 mm. mercury absolute pressure, representing 34.26 per cent by weight of the extract, and having the following properties:

Gravity, degrees A. P. I 17.8 Viscosity at 100 F., centistokes 33.66 Viscosity at 210 F., centistokes 4.17 Viscosity index 6'7 was obtained. This fraction was sulfonated with 50 weight per cent of 95.5 per cent sulfuric acid for 5 hours at room temperature. At the end of the sulfonation period, the mixture separated into two layers. The bottom layer contained waterand aqueous alkali-soluble sulfonic acids free of sludge bodies. The upper layer consisted of unreacted oil and some oil-soluble (mahogany) sulfonic acids. The oil-soluble sulfonic acids were removed by treatment with ethanolamine as described in U. S. Patent No. 2,519,930, referred to above. The unreacted oil thus obtained had the following characteristics:

Viscosity at 100 F., centistokes 31.40 Viscosity at 210 F., centistokes 4.24 Viscosity index -20 Color, NPA

and represented a yield oi 75 per cent oftheiraction subj cted to sulionation. The .oil thus obtained was bl nded with an S. A. E. 50 lubrication oil which had a viscosity index of 33. The data below include the viscosity indices of these blends.

For purposes of comparison and to illustrate the adva tages obtained by treating the :fraction of the furfural extract instead of the entire extract, the data include the viscosity indices ofblends of the same lubricating oil and an unreacted oil prepared by treating the entire extract in the same manner as described above with respect to the fraction of the extract.

Viscosity Index of Volume 1 Ratio of Blend Lubricating 1 Using Using gif Distillate Entire of Extract Extract Comparison of these data shows that the viscosity index of the lubricating oil of 33 viscosity index is increased by adding the unreacted oil obtained from the extract distillate, whereas addition of the unreacted oil obtained from the entire extract to the lubricating oil produces blends of substantially lower viscosity indices.

In the distillation of the extract described, two additional distillate fractions were collected. These fractions, representing 18.7 per centof the extract, boiled in therange of 400 to 513 C. at mm. mercury absolute. They had the following characteristics:

. Viscosity Grams (Oentistokes L) at 100 F.)

These fractions are adapted for use as a cracking stock or fuel oil.

The residue obtained from the bottom of the still represented 44.7 per cent of the extractand had the following characteristics:

Gravity, degrees A. P. I 12.6 Viscosity at 100 F., centistokes 3,100

It was of value as a residual fuel oil.

Example II Example III ,A .furfural extract was prepared and fractionally distilled exactly as in Example I. The fraction boiling between 307 and 400 C. at 10 mm. :mercury absolute pressure was sulfonated with Wei ht per cent of 95.5. percent sulfuriceacid for S-hours at room temperature. The unreacted oil obtained had a viscosity index of 44. Addition of this oil to a lubricating oil having a viscosity index of 33 in volume ratios of lubricating oil to unreacted oil of 8 to 2, 7 to 3, and 6 to 4 produced blends having viscosity indices of 33, 34 and 34, respectively.

It will be understood that results similar to those of the examples can be obtained by treating other furfural extracts in the manner described. As previously stated, it is important to carry out the sulfonation under mild conditions since a principal purpose of the treatment is to obtain a useful oil. By mild conditions is meant conditions which together result in th sulfonation of only the more easily sulfonatable portion of the extract fraction as distinguished from portions which can be sulfonated only under conditions which cause concomitant appreciable oxidation of the oil. These mild conditions preferably include the use of not more than 50 per cent by Weight of the extract fraction of sulfuric acid containing less than per cent H2804, substantially atmospheric temperatures and a timeof treatment of about 3 to 5 hours.

Obviously many modifications and variations of the invention, as hereinbefore set forth, may be made without departin from the spirit and scope thereof, but only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A method of producing a lubricating oil which comprises subjecting a. solvent extract of a lubricating oil distillate stock containing at least 15 per cent, by weight of the solvent extract, of hydrocarbons boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure, to distillation under conditions adapted to minimize cracking, collecting distillate hydrocarbons boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure and constituting at least. 15 ,per cent by weight of the solvent extract, sub- 'jecting said distillate hydrocarbons to a mild sulfonation treatment efiective to sulfonate the more easily sulfonatable of said distillate hydrocarbons but ineffective to cause appreciable oxidation of said distillate hydrocarbons such as to form objectionable amounts of sludge, said mild sulfonation treatmentcorresponding to sulfonationwith about 20 to about 50 per cent by weight of said distillate hydrocarbons of sulfuric acid of about 93 to 98 per cent H2SO4 concentration at substantially atmospheric temperature and witha time of treatment of less than about 5 hours to produce an unreacted oil layer containing dissolved oilesoluble sulfonic acid and a sulfonating agent layer, separating the unreacted oil layer from .the sulfonating agent layer, removing oil-soluble sulfonic acids from said unreacted oil layer, and recovering the resulting lubricating oil.

v2. A method of producing lubricating oil and refined sulfonates which comprises subjecting a solvent extract'of a lubricatin oil distillate stock containing at least 15 per cent by Weight of the solvent extract of hydrocarbons boiling within the range of about 300 to about 400 C. at 10 mm. ,mercury absolute pressure to distillation under conditions adapted to minimize cracking,

collecting distillate hydrocarbons relatively free of vasphaltic materials boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure and consituting at least 15 per cent by weight of the solvent extract, subjecting said distillate hydrocarbons to a mild sulfonation treatment effective to sulfonate th more easily sulfonatable of said distillate hydrocarbons but ineffective to cause appreciable oxidation of said distillate hydrocarbons such as to form objectionable amounts of sludge, said mild sulfonation treatment comprising sulfonating said distillate hydrocarbons with about 20 to about 50 per cent by weight of said distillate hydrocarbons of sulfuric acid containing about 90 to about 100 per cent H2804 for less than about hours, to produce an unreacted oil of improved viscosity index and sulfonic acids substantially free of contaminating insoluble sludge bodies, separating the unreacted oil layer from the sulfonating agent layer, converting the sulfonic acids in the unreacted oil to sulfonates, separating the unreacted oil from the sulfonates, and recovering the resulting unreacted lubricating oil.

3. A method in accordance with claim 2 in which said distillate hydrocarbons constitute 30 to 40 per cent by volume of a furfural extract.

4. A method of producing lubricating oil and refined sulfonates which comprises subjecting a solvent extract of a lubricating oil distillate stock containing at least 15 per cent by weight of the solvent extract of hydrocarbons boiling within the range of about 300 to about 400 C. at mm. mercury absolute pressure to distillation under conditions adapted to minimize cracking, collecting distillate hydrocarbons relatively free of asphaltic materials boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure and constituting at least per cent by weight of the solvent extract, subjecting said distillate hydrocarbons to a mild sulfonation treatment effective to sulfonate the more easily sulfonatable of said distillate hydrocarbons but ineffective to cause appreciable oxidation of said distillate hydrocarbons such as to form objectionable amounts of sludge, said mild sulfonation treatment comprising sulfonating said distillate hydrocarbons with about to about per cent by weight of said distillate hydrocarbons of sulfuric acid of about 93 to 98 per cent by weight H2804 concentration at about atmospheric temperature for less than about 5 hours to produce an unreacted oil of improved viscosity index and sulfonic acids substantially free of insoluble sludge bodies, separating the unreacted oil and the sulfonic acids, removing oilsoluble sulfonic acids from the unreacted oil, and blending a minor amount of the unreacted oil with a major amount of a lubricating oil.

5. A method of producing lubricating oil and refined sulfonates which comprises subjecting a. solvent extract of a lubricating oil distillate stock to distillation to obtain a distillate fraction boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure, subjecting the distillate fraction to a mild sulfonation treatment effective to sulfonate the more easily sulfonatable portion of said distillate fraction but ineffective to cause appreciable oxidation of said distillate fraction such as to form objectionable amounts of sludge, said mild sulfonation treatment comprising sulfonating said distillate fraction with about 20 to about 50 per cent by weight of the distillate fraction of sulfuric acid containing about 90 to about 100 per cent H2SO4 for less than about 5 hours to produce an unreacted oil of improved viscosity index and sulfonic acids substantially free of contaminatinginsoluble sludge bodies, separating the resuiting unreacted oil layer from the sulfuric acid .1

layer, converting the sulfonic acids in the unreacted oil to sulfonates, separating the unreacted oil from the sulfonates, and blending the unreacted oil with a lubricating oil in such proportions that 100 parts by volume of the blended oil contains about 10 to 40 parts of the unreacted oil and about to 60 parts of the lubricating oil.

6. A method of producing lubricating oil and refined sulfonates which comprises subjecting a furfural extract of a lubricating oil distillate stock to distillation to obtain a distillate fraction boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure, subjecting the distillate fraction to a mild sulfonation treatment eifective to sulfonate the more easily sulfonatable portion of said distillate fraction but ineffective to cause appreciable oxidation of said distillate fraction such as to form objectionable amounts of sludge, said mild sulfonation treatment comprising sulfonating said distillate fraction with about 20 to about 50 per cent by weight of the distillate fraction of sulfuric acid containing about 9-3 to about 98 per cent H2804 at substantially atmospheric temperatures for less than about 5 hours-to produce an unreacted oil of improved viscosity index and sulfonic acids substantially free of contaminating insoluble sludge bodies, separating the resulting unreacted oil layer from the sulfuric acid layer, converting the sulfonic acids in the acid oil to sulfonates, separating the um'eacted oil from the sulfonates, and blending the unreacted oil with lubricating oil having an S. A. E. number of at least 40 in such proportions that 100 parts by volume of the blended oil contains about 10 to 40 parts of the unreacted oil and about 90 to 60 parts of the lubricating oil.

7. A method of producing lubricating oil and refined petroleum sulfonates which comprises subjecting crude oil .to distillation at temperatures below 760 F. while passing steam through the charge oil at the rate of about :2 to 10 pounds per barrel of charge oil to produce lubricating oil stock relatively free of olefins and decomposition products, solvent refining the lubricating stock with furfural to produce a rafiinate and an extract fraction containing at least 30 per cent, by weight of said extract fraction, of hydrocarbons boiling within the range of about 300,to about 400 C. at 10 mm. mercury absolute pressure, subjecting the extract fraction to distillation under conditions adapted to minimize cracking, collecting distillate hydrocarbons boiling within the range of about 300 to about 400 C. at 10 mm. mercury absolute pressure and constituting at least 30 per cent by weight of said extract fraction, subjecting said distillate hydrocarbons to a mild sulfonation treatment efiective to sulfonate the more easily sulfonatable of said distillate hydrocarbons but inefiective to cause appreciable oxidation of said distillate hydrocarbons such as to form objectionable amounts of sludge, said mild sulfonation treatment comprising sulfonating said distillate hydrocarbons with about 20 to about 50 per cent by weight 01 said distillate hydrocarbons of sulfuric acid of about 93 to 98 per cent by weight H2804 concentration at about atmospheric temperature and with a time of treatment of about 3 to about 5 hours to produce an unreacted oil of improved viscosity index and sulfonic acids substantially free of sludge bodies, separating the unreacted oil and the sulfonic acids, removing oil-soluble 2,560,479 A 1O sulfonic acids from the unreacted oil, and blend- REFERENCES CITED ing the unreacted oil with a lubricating oil hav- The following references are of record in the ing an S. A. E. number of at least 40 and a visfile of this patent: cosity index about 40 to 60 viscosity index units above the viscosity index of the unreaoted oil in 5 UNITED STATES PATENTS such proportions that 100 parts by volume of the Number Name Date blend oil contains about 10 to 40 parts of the un- 1,989,045 Merrill Jan. 22, 1935 reacted oil and about 90 to 60 parts of the lubri- 2,050,345 Liberthson Aug. 11, 1936 eating oil. 2,068,847 Davis et a1. Jan. 26, 1937 GEORGE RIETHOF. 10 2,330,163 Waldo et a1. Sept. 21, 1943 CHARLES W. MONTGOMERY. GEORGE P. BROWN, JR. 

1. A METHOD OF PRODUCING A LUBRICATING OIL WHICH COMPRISES SUBJECTING A SOLVENT EXTRACT OF A LUBRICATING OIL DISTILLATE STOCK CONTAINING AT LEAST 15 PER CENT, BY WEIGHT OF THE SOLVENT EXTRACT OF HYDROCARBONS BOILING WITHIN THE RANGE OF ABOUT 300* TO ABOUT 400* C. AT 10 MM. MERCURY ABSOLUTE PRESSURE, TO DISTILLATION UNDER CONDITIONS ADAPTED TO MINIMIZE CRACKING, COLLECTING DISTILLATE HYDROCARBONS BOILING WITHIN THE RANGE OF ABOUT 300* TO ABOUT 400* C. AT 10 MM. MERCURY ABSOLUTE PRESSURE AND CONSTITUTING AT LEAST 15 PER CENT BY WEIGHT OF THE SOLVENT EXTRACT, SUBJECTING SAID DISTILLATE HYDROCARBONS TO A MILD SULFONATION TREATMENT EFFECTIVE TO SULFONATE THE MORE EASILY SULFONATABLE OF SAID DISTILLATE HYDROCARBONS BY INEFFECTIVE TO CAUSE APPRECIABLE OXIDATION OF SAID DISTILLATE HYDROCARBONS SUCH AS TO FORM OBJECTIONABLE AMOUNTS OF SLUDGE, SAID MILD SULFONATION TREATMENT CORRESPONDING TO SULFONATION WITH ABOUT 20 TO ABOUT 50 PER CENT BY WEIGHT OF SAID DISTILLATE HYDROCARBONS OF SULFURIC ACID OF ABOUT 93 TO 98 PER CENT H2SO4 CONCENTRATION AT SUBSTANTIALLY ATMOSPHERIC TEMPERATURE AND WITH A TIME OF TREATMENT OF LESS THAN ABOUT 5 HOURS TO PRODUCE AN UNREACTED OIL LAYER CONTAINING DISSOLVED OIL-SOLUBLE SULFONIC ACIDS AND A SULFONATING AGENT LAYER, SEPARATING THE UNREACTED OIL LAYER FROM THE SULFONATING AGENT LAYER, REMOVING OIL-SOLUBLE SULFONIC ACIDS FROM SAID UNREACTED OIL LAYER, AND RECOVERING THE RESULTING LUBRICATING OIL. 